Accordion folding door



Aug. 25, 1964 A. M. Y. DE JONG ACCORDION FOLDING DOOR Filed April 24, 1962 Arron/5x5;

United States Patent 3,145,767 ACCORDION FOLDING DOOR Alf Martin Ysbrand tie .Iong, Stockholm, Sweden, assignor to Ciopay Corporation, Cincinnati, Ohio, a corporation of Maryland Filed Apr. 24, 1962, Ser. No. 189,775 1 Claim. (Cl. 160-231) This invention concerns an improvement in accordion folding doors of the type disclosed in Collins Patent No. 2,667,218, now Reissue No. 25,112.

One embodiment of the Collins invention comprises a folding door, part of which is a sheet of thermoadhesive plastic material that is doubled over along a fold line which becomes the top of the completed door. Heat seals are made in the double over sheet along vertical lines which extend from points adjacent to the fold line at the top to the bottom of the door. These heat seal lines form a series of uniformly dimensioned pockets which are open at the bottom. A series of thin, flat elongated panels, which are of a size to extend from the top of the completed door to the bottom, is inserted into the pockets. The heat seal lines form hinge lines on which the door folds in opening and closing it.

Each of these panels has a slide button affixed to the top thereof in a centered position and each one of these slide buttons is designed to project through a small opening in the plastic sheet material at the top edge of the door for engagement with an overhead track. This track is fastened to the frame of the door at the top of the doorway. The sides of the folding door are finished appropriately to provide a flap at the one side, which may be secured to the jamb at one side of the doorway, and to provide a leading edge, which may be pulled toward and from the jamb at the other side of the doorway. In the embodiment of the Collins invention with which this invention is concerned, the weight of the covering material is carried on the upper ends of the panels; that is, the covering material is continuous from one side of the door, over the top and down the other side of the door.

With the door extended in closed position, the covering material passes over the top of the door on a radius. This radius appears as the trace of an are upon a plane which passes through the extended door from one side to the other, normal to the face of a panel. Otherwise expressed, the upper edge of the extended door, going across the door from the leading edge to the flap edge, forms what might be likened to a rounded, inverted channel. There is no concern for those sections of this channel that make contact with the upper ends of the panels. However, when a door is folded accordion-wise, those sections of the rounded channel between panels, on the hinge lines between panels, collapse to form sharply defined folds in the sheet material. With age and continued use, and particularly in installations at low temperatures, unsightly cracks or tears begin to form in the plastic material along the top of the door at these sharply defined folds. These sharply defined fold lines extend downwardly from the top of the door and first appear as tiny cracks right on the very top edge of the door material, which normally, in extended position, is rounded. The cracking then progresses downwardly from the top to a point where they are unsightly, and under difiicult environmental conditions they progress to a point to expose parts of the panels.

The present invention is specifically directed to a simple, inexpensive solution to the problem caused by the collapse of the material into these sharply defined fold lines which eventually become cracks or tear lines.

The invention is now explained by reference to the accompanying drawings in which:

FIGURE 1 is a diagrammatic elevational view, in

3,145,767 Patented Aug. 25, 1964 which the center section is broken away, of one embodiment of a folding door made in accordance with the teachings of the Collins patent.

FIGURE 2 is a fragmentary, perspective view of the upper portion only of a door of the type shown in FIG- URE 1, illustrating one fold of the door in a semi-extended position.

FIGURE 3 is a view similar to FIGURE 2 showing the door folded accordion-wise to a position in which a sharply defined fold line is formed in the upper edge of the plastic covering material between panels.

FIGURE 4 is an enlarged elevational View illustrating the top portion only of a door incorporating the improvement of this invention.

FIGURE 5 illustrates the condition of a door incorporating the improvement of this invention in the same position as the prior art door shown in FIGURE 2.

FIGURE 6 illustrates the condition of a door incorporating the improvement of this invention in the same position as the prior art door shown in FIGURE 3.

In the embodiment of the Collins invention toward which this invention is directed, the hinge lines between panels are formed into the covering material 10 by two somewhat deeply impressed heat seal lines 11-12 which extend from a point adjacent to the upper edge 13 of the covering material to the very bottom of the door. These lines are spaced apart approximately of an inch and each line is approximately of an inch wide. The space between the upper ends of the lines and the very top of the door is approximately /2 of an inch.

Referring to FIGURE 2, which illustrates the prior art door in a substantially extended position, it may be seen that the doubled over plastic sheet, designated 10, which covers the door passes over top of the panels, designated 15, on an are or radius. The sections of the doubled over sheet at the top of the door passing over the panels is not adversely effected by the folding of the door. It is only in those sections of the top edge of the door between panels that cracking occurs. The top folded edge is formed with openings 13' above each of the panels 15 through which supporting rivets 15' extend. The openings 13 are approximately midway between the longitudinal extensions of each pair of vertical heat seal lines. Inasmuch as there are two heat seal lines, repeated folding can result in one of these lines 11 or 12 becoming a favored hinge line, or both of these lines may alternately become favored hinge lines so that a crack may appear initially in the upper edge of the door over one or both of these heat seal lines. As illustrated in FIGURES 2 and 3, the right one of the two heat seal lines, shown at 12, has become the favored one of the two hinge lines so that a long crack 16 has progressed downwardly from the upper edge of the door. Also, as shown at 17, a small crack has started above heat seal line 11. As has been stated previously, a crack of this type, having started, progresses downwardly and depending upon the age of the plastic material, the use to which the door is put, and to a certain extent the temperature of the environment in which the door is hung, a crack of this type may progress to a point where it passes downwardly along side one or both of the heat seal lines to an extent where the panels within the door are exposed.

The improvement of this invention comprises essentially the impressing of a heat seal line, designated 18 in FIGURE 4, along that area of the upper edge of the door which is above each of the pairs of heat seal lines 11-12, which form the hinge lines between individual panels. This heat seal line preferably is right on, or very close to, the upper edge of the door. This heat seal line need be no wider than /s of an inch, although wider ones work well, and it can be impressed into the upper edge of the door with a heated bar of the same type utilized in forming the vertical lines 11-12 which comprise the hinge lines of the door. It has been determined empirically that the heat seal 18 should continue beyond the outer sides of the vertical heat seal lines 11-12, just how far is difiicult to determine, but it is believed that the ends of the heat seal 17 should be continued at least A of an inch or more beyond the ends.

Reference is now made to FIGURES 5 and 6. It may be seen that the heat seal line 18 illustrated in FIGURE 4 is in the form of a curve which has a trace of an are on a horizontal plane. This is in contrast to the curve at 13 in FIGURE 2 which has a trace of an are on a vertical plane. Going now to FIGURE 6, by comparing this figure with FIGURE 3 it may be seen that instead of the area between panels at the top of the door collapsing to form a sharply defined fold, the folded area forms into a rounded configuration on a substantial radius which, even in the completely folded condition of the door remains rounded, and thereby does not give rise to cracking. Having described my invention, I claim:

In an accordion folding door of the type comprising a cover sheet of plastic material that is doubled over to provide an upper edge for the door and that has vertical heat seal lines to provide a series of pockets and hinge lines between said pockets, said vertical heat seal lines extending from points adjacent to said upper edge to the bottom of said cover, a series of panels freely received in said pockets, a support rivet extending vertically upwardly from the upper ends of said slats to suspend said panels from an overhead track whereby the panels support said cover sheet, said upper edge of said cover sheet formed with a plurality of openings through which said support rivets extend, that improvement comprising a horizontal heat seal line at the upper edge of said cover above each of said hinge lines and between said openings, and said horizontal heat seal lines projecting inwardly of the side edges of said panels.

References Cited in the file of this patent UNITED STATES PATENTS Schade July 28, 1953 Collins Jan. 26, 1954 Sween Apr. 1, 1958 

